Fountain pen



FIG. 1 is a perspective view of front, top and left side of a fountain pen showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a front view indicating a state that a cap is detached from a main body. 

CLAIM The ornamental design for a fountain pen, as shown and described. 